C5/C6 Corvette Oil Change - Corvetteconomics 101

A C5/C6 Oil Change The Right Way

As I mentioned earlier, the C5 oil drain plug is at the front of the oil pan, so the nose of the car should be lower than the rear in order for the oil to drain forward. Having the rear of the C5 elevated about 2-4 inches higher than the rear will do nicely to help evacuate the old oil. On the C6, the drain plug is next to the oil filter, so the vehicle should be level for changing the oil, rather than having the rear slightly elevated a la C5.

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Before removing the drain plug, however, open the hood and remove the oil filler cap and pull the dipstick up a bit so that it's not fully seated. This helps to relieve pressure and enables the oil to drain a bit faster. I also suggest that the engine oil be warm when doing the oil change; warm oil is thinner and flows more quickly than cold oil.

Next, it's time to position the drain pan underneath and slightly forward of the drain plug. Use your 15mm box wrench or socket and ratchet to loosen and, ultimately, remove the drain plug. Give it at least 15 minutes for the oil to drain. When the flow has slowed down to a thin trickle (or better yet, intermittent drops), you can replace the drain plug; 15 lb-ft is the factory torque spec. I use the "feel" method, however. That is, I tighten it until it feels tight enough to me. Be sure not to over-tighten the plug-it's a bear to remove at the factory spec, so it may well be impossible to get it out without ruining it if you go too tight. Now you're ready to move the drain pan under the oil filter and remove it.

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A word about magnetic drain plugs is in order here. For about $5.00 you can replace the stock drain plug with an aftermarket magnetic drain plug available from Mid America Motorworks and other suppliers. In the overall scheme of things, $5 is very cheap insurance to help safeguard your engine from possible damage that can be caused by stray, minute steel or iron particles that may be suspended in your oil circulatory system. At the very least, five bucks will buy you a lot of peace of mind.

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If you use K&N Oil Filters, like I do, here's a little tip to help keep things neater. The K&N filters have a 1-inch nut welded to the bottom of the filter, which makes for easy removal using a 1-inch open-end wrench. I loosen the filter about 1/2 turn, then slide a plastic bag over the filter and unscrew it the rest of the way by hand. As the filter comes off, the plastic bag catches it and the resultant dripping oil, thus preventing it from getting on the garage floor or driveway surface. Ostensibly, this trick will work with other brands of filters as well, once they're loose enough to be spun off by hand.

And, if you really want to get some extra engine protection, you might consider investing in an oil filter magnet for a few dollars more. Mid America Motorworks has a nice disc-shaped unit that grabs onto the bottom of an AC/Delco filter or other smooth-bottomed filter and traps and holds any stray ferrous particles that enter the filter from the lubrication stream. This disc-shaped filter magnet doesn't work with the K&N filters due to the 1-inch removal nut abutment I mentioned earlier, so I use a cylindrical FilterMag wrap-around oil filter magnet available from www.filtermag.com.

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GM specifies that you must use oil that meets or exceeds General Motors standard GM4718M (synthetic 5W30) in order to maintain your new factory warranty. However, not all synthetic oils meet this standard. So be sure to purchase oil that meets or exceeds this standard. GM uses Mobil 1 5W30 as the factory fill on the assembly line at Bowling Green. I use Royal Purple 5W30 synthetic, but that's my personal preference. You can use any brand you wish as long as it meets or exceeds the GM standard.

I prefer to use Royal Purple 5W30 Synthetic and K&N filters for my '98 C5. I always keep a quart of oil in the trunk, too.

I recommend installing a magnetic drain plug and using an oil filter magnet for a bit of added protection against stray metal particles floating around in your oil. A disc-shaped magnet like this one works well with flat-bottomed filters like the AC/Delco unit.

I attach a FilterMag (www.filtermag.com) to my oil filter as added insurance. The strong, reusable magnet attracts and holds any minute stray steel particles to the side of the filter rather than letting them circulate throughout the engine.

Here's a view of the C5 oil pan from under the car. The "batwing" extensions on both sides of the pan were added by GM engineering after severe oil starvation was encountered on hard cornering during development of the C5. These extensions necessitate additional drain time for all the oil to evacuate from the oil pan.

A pair of gradual-incline ramps like these Rhino Ramps make elevating the front of your C5 a breeze, and they're specifically designed for cars with low ground clearance.

A cushioned lift platform insert like this one from The Eastwood Company simply drops into the trolley jack in place of the stock platform and it protects the lifted surface from scratches and marring.

You can also get a special jack insert like this one that fits the C5/C6 chassis frame lifting holes precisely.

Another lifting option is to get a set of aluminum lift pads that install in the four chassis frame lifting holes.

These plastic lift plates also come as a set of four. They snap into the frame lifting holes and can be left in place if you wish.

Here's the way your C5 should look when you're ready to drain the oil. The rear of the car should be slightly higher than the front so the oil will drain out completely (remember, the drain plug is at the front of the oil pan on C5s-for C6s, keep the car level).

Pop your hood, remove the oil filler cap, and pull out the dipstick to promote air circulation which will aid in oil drainage.

Position the trolley jack under the rear cradle to elevate the back of the car and pump it up all the way. A low-profile hydraulic trolley jack is best for the low ground clearance of C5s and C6s. Position jackstands on both sides of the frame right at the oblong jack hole openings (with lift pads inserted) and lower the jack so that the jackstands are supporting the rear of the car.

The red arrow shows the jacking point on the front crossmember. Jack up the front end and support it with jackstands on both sides of the frame at the front oblong frame lifting hole openings, again using lift pads.

Do not get under the C5 or C6 until it is completely supported by the four jackstands. Nothing can ruin your day like having a 3,500-pound Corvette crashing down on you.

If you have a creeper, you can use it to get under the car, although an old door mat, a piece of scrap carpet, or even a flattened cardboard box will serve as a separator between your back and the driveway pavement. Position your oil drain container under the drain plug and remove it with a 15mm wrench. Nitrile or latex gloves are recommended, since this will definitely be a bit messy. A droplight comes in handy so you can see what you're doing under the car, too.

I suggest you let the oil drain for a full 15 minutes (or longer) to make sure as much of it evacuates the engine as possible. It will be a full thick stream at first, dwindling down to a trickle shortly. I don't replace the drain plug until it becomes an intermittent drip. After replacing and tightening the plug, reposition the drain container and remove the oil filter (again, this can be messy). Pre-fill the filter with new oil and coat the rim gasket with it (rub it on with your finger), then screw the filter on as far as you can by hand and give it another half turn with a filter wrench. The K&N filters have a built-in nub on them which makes removing and tightening them with a 1-inch wrench a snap.

Lower the rear of the car and place a bubble level on the door sills to verify that the car is level. Proceed to add oil to the engine and check the dipstick, adding oil as required to bring it to the full marks. Job done!

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